The present invention relates to seat adjusters used in a motor vehicle and more particularly to those adjusters which provide for improved height adjustments of the seat through the manual movement of linkages. Such manual vertical seat adjusters are adapted to adjust upward and downward to a specific height depending upon the passenger's personal preferences. U.S. Pat. No. 3,149,815 "Manual Seat Adjuster", the entire disclosure of which is hereby incorporated by reference, discloses a seat adjuster constructed such that the frame of the vehicles seat could be displaced upward and downward through the use of linkage means provided on the front and rear portions of the seat and supported by brackets fixed to the vehicle floor. The U.S. patent also discloses a so-called "anti-back drive" system.
In the known vertical seat adjusting device, the linkage provided for moving the vehicle seat was designed to lift the vehicle seat while retaining a parallel horizontal seat plane. However, when taking a passenger's comfort into consideration, it is preferable to have the rear of the seat lifted higher than the front of the seat. The prior art does not show any consideration given to the thought of a staggered vertical lift of a passenger seat in order to provide for more passenger comfort.
Therefore, the conventionally known device has disadvantages in that a passenger seated in the vehicle cannot get into a comfortable position on the vehicle's seat.